We look at the crown as a maintenance item. We keep a eye on them and the rest of the barrel with the bore scope. If they look to be losing their sharpness (from cleaning) Tad will clean them up. Dialing the barrel in takes the bulk of time. Usually it very little removed to sharpen it back up. Carrie and I almost always shoot together and will shoot the same rifle. If its a 6 card match (x2) that rifle will see a cleaning rod in and out 72 times for that match. That rifle will more than likely see a crown sharpening mid season.
Todd